The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
Powertrain systems include transmission devices and internal combustion engines, including configurations in which the engine executes autostop and autostart maneuvers during ongoing powertrain operation. Such powertrain systems may transmit torque originating from multiple torque generative devices, e.g., the engine and a non-combustion torque machine, through the transmission device to an output member that may be coupled to a driveline. Such powertrain systems include hybrid powertrain systems and extended-range electric vehicle systems. Control systems for operating such powertrain systems operate the torque-generative devices and apply torque transfer elements in the transmission to transfer torque in response to operator-commanded output torque requests, taking into account fuel economy, emissions, driveability, and other factors. The non-combustion torque machines may include electric machines that are operative as motors or generators to generate a torque input to the transmission independently of a torque input from the internal combustion engine. The torque machines may transform vehicle kinetic energy, transferred through the vehicle driveline, to electrical energy that is storable in an electrical energy storage device. A control system monitors various inputs from the vehicle and the operator and provides operational control of the hybrid powertrain, including controlling transmission operating state and gear shifting, controlling the torque-generative devices, and regulating the electrical power interchange between the electrical energy storage device and the electric machines to manage outputs of the transmission, including torque and rotational speed.
During both engine autostop maneuvers and engine autostart maneuvers, compression torque pulses are generated in individual engine cylinders and transmitted to an engine crankshaft and a transmission input member, which may result in objectionable vibrations reaching a vehicle operator at resonant frequencies for the powertrain and various driveline components. The compression torque pulses can disturb engine output torque and can result in objectionable physical vibration and audible noise.